Design of a Rheometer for Time-Dependent Gel Rheology

The key to the successful dissemination of gel propulsion is a comprehensive understanding of the gel rheological flow properties that affect atomization, combustion, and throttling performance. Time-dependent non-Newtonian phenomenological models will beexamined and compared with existing AMCOM/TRW gel data and available literature on gel rheology to identify the most suitable candidate models. The models selected from this analysis will be implemented as a user subroutine in the CFD-ACE+ code. Thismodeling effort will be critical in supporting a first principles examination of the measurement process associated with unsteady gel flow. A first principles characterization must be made to guarantee that the relationships between the time-dependentrheological properties at shear rate from to 5,000 s-1 to 200,000 s-1are fully understood and applicable.In order to fully quantify these time-dependent properties, a pressure drop/flow rate rheometer capable of thorough experimental examination of various flow fixtures will be conceptualized during Phase I. The most promising fixtures, identified as thosethat will accurately measure the time dependent characteristics of gel propellants within a propulsion system flow passage will be identified. A detailed set of rheometer prints will be prepared during the option program. During Phase II, the rheometer andtest fixtures will be fabricated and the models validated for gel flows between -40 ¿C and 70 ¿C and shear rates from 5000 sec 1 to 200,000 sec 1. Commercial applications include production and quality control in the cosmetics and pharmaceutical industries where ointments, creams, and lotions actually exploit thixotropic behavior in their very use. In addition, the food industry is a prime target,where mixing of batters, jellies, spreads, and innumerable other products necessitate understanding of non-Newtonian Rheology to maintain quality control and high production rates. Increased understanding of hematic rheological properties could have farreaching implications for renal patients.